The ratio between the number of girls and boys is 7: 13 respectively. What is the percentage of girls in the class?

Options

A. 35
B. 55
C. 45
D. Cannot be determined

Answer

To find the percentage of girls in the class given the ratio of girls to boys is 7:13, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Ratio**: The ratio of girls to boys is given as 7:13. This means that for every 7 girls, there are 13 boys.

2. **Calculate the Total Parts**: To find the total number of parts represented in the ratio, we add the parts of girls and boys together:
\[ \text{Total parts} = 7 + 13 = 20 \]

3. **Find the Fraction of Girls**: The fraction of the class that is girls can be calculated by taking the number of girls (7 parts) and dividing it by the total number of parts (20):
\[ \text{Fraction of girls} = \frac{7}{20} \]

4. **Convert Fraction to Percentage**: To convert the fraction of girls into a percentage, we multiply by 100:
\[ \text{Percentage of girls} = \left(\frac{7}{20}\right) \times 100 \]

5. **Perform the Calculation**:
- First, calculate \( \frac{100}{20} = 5 \).
- Then multiply by 7:
\[ 5 \times 7 = 35 \]

6. **Final Result**: The percentage of girls in the class is:
\[ \text{Percentage of girls} = 35\% \]

### Final Answer:
The percentage of girls in the class is **35%**.

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